Tension prevailed in downtown Haifa today, and reinforced police details were on the alert for possible further trouble, following a riot Friday night in which five persons were seriously wounded, many others suffered injuries, and 50 men were detained by the harassed police.

Among the wounded are a number of policemen. Among those detained is David Ben Haroush, self-proclaimed “leader” of the Wadi Salib quarter here, where the residents are mostly immigrants from North Africa.

The latest in the series of riots was staged Friday night, when the local branch of the Mapai Party was conducting an election rally in a downtown motion picture theater. Crowds gathered around the theater, intent, evidently, either on disrupting the meeting or preventing the audience from entering the house.

When police tried to disperse the crowd, rioters attacked the police, some mounting to rooftops in the area, throwing stones at the policemen. During the attempt by police to enter one house from which stones were being cast, one shot was fired.

The police surrounded the house whence the shot had come and ordered the occupants to emerge. Four men, including Mr. Ben Haroush, came out. Police said that the leader of the North African immigrants was in possession of the pistol from which the shot had been fired.

Previous riots by North African immigrants had taken place in this city, in Beersheba and at Migdal Haamek. Police said they have discovered no direct links between the ear-lier Haifa riot and those in the other cities. However, it is felt that dissatisfaction among some North African immigrants, perhaps inflamed by election propaganda, may have been a common denominator underlying the entire series of disturbances.